It was discovered that PyOpenSSL, a Python wrapper around the OpenSSL
library, does not properly handle certificates with NULL characters in
the Subject Alternative Name field.

A remote attacker in the position to obtain a certificate for
'www.foo.org\0.example.com' from a CA that a SSL client trusts, could
use this to spoof 'www.foo.org' and conduct man-in-the-middle attacks
between the PyOpenSSL-using client and the SSL server.

For the oldstable distribution (squeeze), this problem has been fixed in
version 0.10-1+squeeze1.

For the stable distribution (wheezy), this problem has been fixed in
version 0.13-2+deb7u1.

For the unstable distribution (sid), this problem has been fixed in
version 0.13-2.1.

We recommend that you upgrade your pyopenssl packages.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: http://www.debian.org/security/